1. Field of Endeavor
The present invention relates to electrochemical energy storage systems and more particularly to a monolithic three-dimensional electrochemical energy storage system on an aerogel or nanotube scaffold.
2. State of Technology
Electrochemical energy storage systems are used for a wide variety of applications including but not limited to wireless communications, portable computing, uninterruptable power systems, various robotic systems, including but not limited to well-known robots such as Talon, electric and hybrid electric vehicles, more exotic vehicular applications such as manned and unmanned underwater vehicles, and various aerospace applications including satellites. Some of the specific energy storage technologies include a wide range of primary and secondary battery systems. The primary battery systems include: (1) conventional primary batteries; (2) air breathing batteries, such as zinc-air and lithium-air systems; (3) seawater batteries, including magnesium-seawater systems; and (3) thermal batteries. Secondary batteries to be discussed in the course include: (1) lead-acid; (2) silver-zinc; (3) nickel-cadmium; (4) nickel-metal hydride; (5) lithium-ion; (6) sodium-beta batteries, including the sodium-sulfur and ZEBRA systems; (6) nickel-hydrogen; and (7) regenerative fuel cells. The two most energy dense anode materials are hydrogen, followed by lithium. The most energy dense cathode material is oxygen. While in terrestrial fuel cells, the oxygen can be extracted from the atmosphere, in space-based and undersea systems, this oxidant must be stored. Batteries are traditionally energy storage devices with high energy density but low power density. Most of the energy is stored in bulk electrode material, and both chemical reaction as well as ionic transport through the porous active layer limit power output. The power density of a battery could be substantially improved if the transport resistance could be decreased while maintaining or increasing the surface area of the electrodes. Previous attempts to do so have utilized much thinner active layers (5-10 um thick) or solid electrolytes with low thicknesses, such as LiPON. The total surface area of these devices has typically been very low, however, and resulted in a severe reduction of energy density. A successful solution will require the combination of a large surface area and a thin electrolyte layer